The invention relates to an internal combustion engine with an exhaust gas turbocharger having an exhaust gas turbine with a turbine wheel arranged in an exhaust duct and an exhaust gas release arrangement disposed in the exhaust duct upstream of the turbine wheel.
DE 42 32 400 C1 discloses an exhaust gas turbocharger with variable turbine geometry for an internal combustion engine. The turbocharger includes an annular insert arranged between a spiral turbine inlet conduit of the turbine of the exhaust gas turbocharger and a turbine wheel so as to be slideable such that the flow cross-section for the exhaust gas is adjustable depending on certain operating parameters of the internal combustion engine.
The arrangement however, has the disadvantage that, upon reaching a certain load limit, the gas admission cross-section is restricted to such a degree that the exhaust gas flow through the turbine of the exhaust gas turbocharger is insufficient to generate sufficient power for proper operation of the compressor of the turbocharger.
DE 29 01 041 C2 discloses an exhaust gas turbocharger, which includes an exhaust gas bypass duct and a pressure control valve by way of which it can be adapted to the operating state of an internal combustion engine. The internal combustion engine and the exhaust gas turbocharger are to be protected by way of the exhaust gas bypass duct and the pressure control valve from overloads.
The arrangement, however, is complicated as far as its design and its control requirements are concerned. In addition, it requires complex passageways, which generate undesirable turbulence and consequently power losses for the exhaust gas turbocharger.
Also, exhaust gas discharge valves are known in the art by way of which exhaust gas is released from exhaust gas duct systems. They serve to eliminate load peaks of the internal combustion engine and of the exhaust gas turbocharger.
Such exhaust gas discharge valves, however, have the disadvantage that they permit to limit the pressures only in the exhaust gas duct system. The exhaust gas discharge valves open when a certain load limit is reached and release the exhaust gas from the exhaust gas duct system. This causes a sudden pressure drop in the exhaust gas duct system resulting in a power loss in the exhaust gas turbocharger.
It is therefore the object of the present invention to provide an internal combustion engine with an exhaust gas turbocharger in which an overloading of the exhaust gas duct system and of the internal combustion engine by an excessive charge air pressure is avoided and, during motor braking operation as well as power operation of the engine, an air flow to the engine is maintained as it is needed for optimal operation of the internal combustion engine.